The structure of phosphate-binding protein at 1.7 w resolution was solved and published in 1990 (Luecke & Quiocho, Nature 347, 402-406). With the recently installed 2q extension of the MAR scanner at beamline 7-1 we have collected ultra-high resolution data to 1.02 w for phosphate-binding protein from one frozen native and one frozen single-site mutant (T141D) mutant. We are in the process of refining the data with the program SHELXL (Sheldrick, G_ttingen). Initial F o-Fc maps show peaks at the positions where many of the hydrogens in the active site are expected. We hope to be able to resolve the protonation state of the bound inorganic phosphate. The phosphate is bound by 12 hydrogen bonds. There are no solvent molecules within 8 w of the completely sequestered phosphate anion. The current R-factor is 14% for all data to 1.02 w, the RFREE is 18.7%.